Organic wires interface to body

PORTLAND, Ore.  Linking electronics to medical devices like pacemakers and insulin pumps requires the careful monitoring of foreign metallic and semiconducting materials to ensure the body does not reject them.

Researchers at Johns Hopkins Univeristy think they have a better idea about how to do this: use self-assembling organic wires made from naturally occuring proteins.

"Biology doesn't really have metals, so the idea would be to use these [organic wires] to mimic metallic or other semiconducting components used, for example, in pacemakers or other devices where you need to supply electrical current," said professor John Tovar at Johns Hopkins University.

John Tovar

"If we can use these structures as an organic surrogate for these inorganic or unnatural materials, then we might be able to better bridge the interface" between man and machine, Tovar added.

So far, the self-assembling protein sequences have proven they can achieve micron-long organic wires that are only about six nanometers in diameter--much smaller that the metallic wires used in current medical implants. Their electron mobility has yet to be accurately measured, but the researchers expect them to be on a par with other conductive polymers--that is, less than metals--but good enough for the relatively slow speeds associated with medical implant functions.

If the technique can be perfected, it may someday be possible to not only make better pacemakers and other medical implants, but also to potentially bypass injured spinal cords to restore movement to paralyzed limbs.

The organic material used derive their self-assembling principles from the formation of plaques associated with Alzheimer's disease called amyloids. Besides harnessing amyloids to make organic wires, Tovar's research also may uncover methods of preventing, or at least monitoring, their formation in Alzheimer's patients. The goal is to eventually prevent or reverse their damaging effects.